I know you had plans to hang out with someone and shopping was a reason(excuse to get out). But People are flaky I wouldn’t let them waste my time to wait on their call. Always do you! Just get out/be out anyways, go to the gym, go to the bar, go shopping at the mall and if they call, great, if not at least you didn’t waste time waiting for them. You might meet other people at the bar (food) and gym.
I wouldn’t expect anything from anyone without building a rapport I can count on. A good history of us going out.
Also, She may have been expecting you to call, even though she said she would.